This invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to toner compositions with surface additives. In embodiments the present invention is directed to negatively charged conductive magnetic brush toners comprised of polyester resins, especially certain crosslinked extruded polyesters, pigment, and specific surface additives of, for example, metal salts of fatty acids, and silica particles, such as fumed silicas available from Cabot Corporation as TS530.RTM., which additives are present in certain important amounts, reference for example copending patent application U.S. Ser. No. 379,821, the disclosure of which is totally incorporated herein by reference. Also, the toner in embodiments may contain in certain important amounts a third additive of metal oxides, preferably titanium oxide (TiO.sub.2). Further, in embodiments the present invention relates to negatively charged conductive magnetic brush toners especially suitable for hybrid jumping development, which toners are comprised of polyester resins, especially certain crosslinked extruded polyesters, carbon black pigment, and specific surface additives of a mixture of fumed colloidal silica particles and metal salts of fatty acids, preferably zinc stearate, which additives are present in certain important amounts such as for each additive about 0.2 to about 0.5 weight percent. The developer for the aforementioned toners is comprised of carrier coated with a polymer, such as polymethylmethacrylate, and wherein the coating contains a conductive component like carbon black, such VULCAN 72R.RTM. available from Cabot Corporation. The toner and developer compositions of the present invention are useful in a number of known electrostatographic, such as xerographic, imaging and printing systems including printing methods with lasers.
In embodiments, the conductive magnetic brush developers of the present invention can be selected for hybrid jumping development, hybrid scavengeless development, and similar processes, reference U.S. Pat. Nos. 4,868,600; 5,010,367; 5,031,570; 5,119,147; 5,144,371; 5,172,170; 5,300,992; 5,311,258; 5,212,037; 4,984,019; 5,032,872; 5,134,442; 5,153,647; 5,153,648; 5,206,693; 5,245,392; 5,253,016, the disclosures of which are totally incorporated herein by reference. The aforementioned developers, which can contain a negatively charging toner, are suitable for use with laser or LED printers, discharge area development with layered flexible photoconductive imaging members, reference U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference, and organic photoconductive imaging members with a photogenerating layer and a charge transport layer on a drum, light lens xerography, charged area development on, for example, inorganic photoconductive members such as selenium, selenium alloys like selenium, arsenic, tellurium, hydrogenated amorphous silicon, trilevel xerography, reference U.S. Pat. Nos. 4,847,655; 4,771,314; 4,833,540; 4,868,608; 4,901,114; 5,061,969; 4,948,686 and 5,171,653, the disclosures of which are totally incorporated herein by reference, full color xerography, and the like, reference for example the Xerox Corporation 4850.RTM.. In embodiments, the developers of the present invention are preferably selected for imaging and printing systems with conductive magnetic brush development as illustrated, for example, in U.S. Pat. No. 4,678,734, the disclosure of which is totally incorporated herein by reference, and wherein there is enabled in embodiments high development levels, development to substantially complete neutralization of the photoreceptor image potential, development of low levels of image potentials and increased background suppression. Further, the toners of the present invention are free of charge enhancing additives like cetyl pyridinium chloride, thereby minimizing or avoiding environmental problems; and moreover no wax is present with the developers of the present invention, thereby avoiding wax escape and smudging of the developed images.
With the developers of the present invention wax, such as low molecular weight waxes like polypropylene, or polyethylene, and charge additives are avoided; low melting polyesters are selected as the toner resin permitting, for example, lower fuser energies; and the toner size is, for example, from about 7 to about 15 and preferably 9 microns in average volume diameter as determined by a Coulter Counter and narrow GSD in embodiments, for example about 1.3. Additionally, the developers of the present invention in embodiments enable high levels of toner flow, for example from about 7 to about 10 grams per minute, rapid admix of, for example, about 30, and preferably 15 seconds or less, as determined by the charge spectrograph, a toner tribo of from about -15 to about -25 with the two additives, and from about -6 to about -12 for three additives, and high levels of developer conductivity, for example 10.sup.-8 (ohm-cm).sup.-1 at a 3 percent toner concentration. Moreover, in embodiments the surface additive of a fatty acid salt like zinc stearate functions primarily as a conductivity component and the fumed silica functions primarily as a flow aid, toner blocking avoidance component, and for assistance in achieving excellent admix characteristics. The third surface additive of metal oxides, like titanium dioxide, in the surface mixture assists in achieving a combination of excellent toner flow, superior admix, and acceptable blocking characteristics, and moreover, the three surface additive mixture assists in controlling the tribocharge of the toner.
Toner and developers with toner additives like wax and surface additives of, for example, metal oxides, and colloidal silicas are known. Toners with polyesters, including extruded polyesters, are also known, reference U.S. Pat. No. 5,227,460, the disclosure of which is totally incorporated herein by reference. In U.S. Pat. No. 4,795,689, there is disclosed an electrostatic image developing toner comprising as essential constituents a nonlinear polymer, a low melting polymer, which is incompatible with the nonlinear polymer, a copolymer composed of a segment polymer, which is at least compatible with the nonlinear polymer, and a segment polymer, which is at least compatible with the low melting polymer, and a coloring agent, see the Abstract, and columns 3 to 10 for example; and U.S. Pat. No. 4,557,991 discloses a toner for the development of electrostatic images comprised of a certain binder resin, and a wax comprising a polyolefin, see the Abstract; also see columns 5 and 6 of this patent and note the disclosure that the modified component shows an affinity to the binder and is high in compatibility with the binder, column 6, line 25.
Developer and toner compositions with certain waxes therein, are known. For example, there are illustrated in U.K. Patent Publication 1,442,835, the disclosure of which is totally incorporated herein by reference, toner compositions containing resin particles, and polyalkylene compounds, such as polyethylene and polypropylene of a molecular weight of from about 1,500 to about 20,000, reference page 3, lines 97 to 119, which compositions prevent toner offsetting in electrostatic imaging processes. Additionally, the '835 publication discloses the addition of paraffin waxes together with, or without a metal salt of a fatty acid, reference page 2, lines 55 to 58. Also, in U.S. Pat. No. 4,997,739, there is illustrated a toner formulation including polypropylene wax (M.sub.w : from about 200 to about 6,000) to improve hot offset. In addition, many patents disclose the use of metal salts of fatty acids for incorporation into toner compositions, such as U.S. Pat. No. 3,655,374. Also, it is known that the aforementioned toner compositions with metal salts of fatty acids can be selected for electrostatic imaging methods wherein blade cleaning of the photoreceptor is accomplished, reference U.S. Pat. No. 3,635,704, the disclosure of which is totally incorporated herein by reference. Additionally, there are illustrated in U.S. Pat. No. 3,983,045 developer compositions comprising toner particles, a friction reducing material, and a finely divided nonsmearable abrasive material, reference column 4, beginning at line 31. Examples of friction reducing materials include saturated or unsaturated, substituted or unsubstituted, fatty acids preferably of from 8 to 35 carbon atoms, or metal salts of such fatty acids; fatty alcohols corresponding to said acids; mono and polyhydric alcohol esters of said acids and corresponding amides; polyethylene glycols and methoxy-polyethylene glycols; terephthalic acids; and the like, reference column 7, lines 13 to 43. Toners with colloidal silicas, like AEROSIL.RTM. are also known.
Described in U.S. Pat. No. 4,367,275 are methods of preventing offsetting of electrostatic images of the toner composition to the fuser roll, which toner subsequently offsets to supporting substrates, such as papers, wherein there is selected toner compositions containing specific external lubricants including various waxes, see column 5, lines 32 to 45.
There are various problems observed with the inclusion of polyolefin or other waxes in toners. For example, when a polypropylene wax is included in toner to enhance the release of toner from a hot fuser roll, or to improve the lubrication of fixed toner image it has been observed that the wax does not disperse well in the toner resin. As a result, free wax particles are released during the pulverizing step in, for example, a fluid energy mill and the pulverization rate is lower. The poor dispersion of wax in the toner resin and, therefore, the loss of wax will then impair the release function it is designed for. Scratch marks, for example, on xerographic developed toner solid areas caused by stripper fingers were observed as a result of the poor release. Furthermore, the free wax remaining in the developer will build up on the detone roll present in the xerographic apparatus causing a hardware failure. With the toners of the present invention, a wax is not present thereby avoiding or minimizing the aforementioned problems.
Illustrated in copending U.S. patent application Ser. Nos. 331,444 and 331,441, the disclosures of which are totally incorporated herein by reference, are toners with surface additive mixtures of silica, polyvinylidene fluoride, a KYNAR.RTM., and strontium titanate.
Illustrated in copending U.S. patent application Ser. No. 379,822, filed concurrently herewith, is a developer composition comprised of negatively charged toner particles comprised of crosslinked polyester resin particles, pigment particles, and a surface additive mixture comprised of metal salts of fatty acids in an amount of from about 0.2 to about 0.5 weight percent, and silica particles in an amount of from about 0.2 to about 0.5 weight percent; and carrier particles comprised of a core with a coating thereover containing a conductive component; U.S. Ser. No. 379,822, filed concurrently herewith, illustrates a developer composition comprised of a negatively charged toner composition comprised of crosslinked polyester resin particles, pigment particles, wax component particles, a compatibilizer and a surface additive mixture comprised of metal salts of fatty acids, silica particles and metal oxide particles; and carrier particles comprised of a core with a polymer coating or mixture of polymer coatings; and wherein said coating or coatings contain a conductive component; and U.S. Ser. No. 379,224, filed concurrently herewith, illustrates an insulating developer composition comprised of resin particles, pigment particles, wax component particles, compatibilizer, and a surface additive mixture comprised of metal salts of fatty acids, silica particles, and metal oxide particles; and carrier particles comprised of a ferrite core with a polymer coating or mixture of polymer coatings; and wherein said developer is of a conductivity of from about 10.sup.-14 to about 10.sup.-16 (ohm-cm).sup.-1, the disclosures of which are totally incorporated herein by reference.